Imaging circuits conventionally comprise a matrix of pixels of which each pixel comprises a photodiode and a transfer circuit configured to transfer the charge of the pixel to a processing circuit. The processing circuit can comprise an analog-digital converter.
In the global shutter imaging circuits, the charges of the pixels can be transferred successively by row. That is all the charges of the pixels of the first row will be transferred simultaneously, then those of the second row, and so on to the last row of the matrix.
In such imagers, each column of the matrix of pixels is associated with processing circuitry, which will be successively connected to each pixel of the column in order to successively transfer the charges of all the pixels.
In order to transfer the charge of a pixel to the processing circuit, it is conventionally appropriate to polarize, by a polarization current, a pixel charge transfer circuit, in particular the follow up transistor in an architecture with three transistors (3T architecture) or with four transistors (4T architecture) well known to the person skilled in the art.
In order to transfer the charges of the pixels of a complete row of the matrix of pixels, it is accepted practice to generate a number of polarization currents equal to the number of columns of the matrix of pixels, these polarization currents having to be identical as far as possible.
Now, the transfer circuits of one and the same imaging circuit are conventionally coupled to one and the same metal track of a ground circuit.
And, it has been observed that, in the images comprising matrices of pixels having a significant number of columns, typically several thousands of columns, the generation of the polarization currents for each column can result in variations of the ground potential along the ground track, and therefore result in polarization current values which vary as a function of the position of the column in the matrix of pixels. That can cause a disturbance to the correct operation of the imaging device.